Statistics show that 993 of every 1000 pieces of luggage that are checked in by the traveler for airline flight handling do arrive with the traveler at the flight destination. Given the volume of luggage on flights worldwide, those seven lost pieces equate to roughly 30 million pieces of luggage each year that are miss-placed by the airlines. Of the seven lost pieces of luggage, five are found and returned by the airline to the traveler on average within 72 hours, but two remain lost.
During the check-in process, luggage is tagged and banded on the outside by the airline with a special QR code (Quick Response Code) and flight and traveler identification. Sometimes the tags are ripped off or damaged during the loading and unloading process. Sometimes luggage misses a flight or is loaded onto a different airplane and ends up in a different destination airport. Sometimes luggage is miss-handled at an intermediate airport, where the traveler disembarks one flight and continues on another. Coordination between the traveler and the airline for notification and return of lost luggage can be very time-consuming, difficult and stressful. The entire process for the airline relating to tracking luggage, returning lost luggage, and compensating the traveler is extraordinarily expensive. Lost luggage related expense is reported by airlines to cost the industry over $3.5 billion each year.
With the advent of satellite technology, it has become possible for devices such as mobile phones to achieve precise navigation location awareness under certain circumstances using a technique called GPS (Global Positioning System). However, at least 4 issues prevent GPS from being used effectively for tracking airline luggage:                1. In the United States, the FCC has directed the FAA to require of all airlines that certain electronic devices, including mobile phones with or without GPS enablement, remain disabled and in an “off” status during air flight. Such direction is apparently necessary due to possible radio frequency interference with airline industry frequencies used by the airlines and traffic control tower personnel. The US prohibition of activation and use of certain electronic devices during air flight is followed almost universally by other airlines worldwide.        2. Most GPS devices require at least indirect line-of-sight with the sky and satellite in order to function. As such, GPS typically works poorly if at all inside airports.        3. GPS enabled devices are expensive for the traveler to place inside every piece of luggage.        4. Any information concerning luggage location by a traveler's GPS device would have to be shared with the airline to be of any use in recovering the luggage.        
Not to be confused with GPS, GSM (Global System for Mobile Communication) is defined as a cellular network, which means that cell phones connect to it by searching for terrestrial cell towers in the immediate vicinity. GSM was developed by ETSI (European Telecommunication Standards Institute) as an international standard. GSM includes GPRS (General Packet Radio Service) for circuit switched data transport of packets.
An SMLC (serving mobile location center) is a network element in GSM cellular networks that resides in the BSC (Base Station Controller) of a Mobile Switching Center. A purpose of an SMLC is to calculate the network-based location of mobile phones. An SMLC may control several LMUs (Location Measurement Units) which are housed on towers and which measure radio signals to help find mobile phones in the area served by the SMLC. It can calculate location using the TA (Timing Advance) method.
Radio resource location services (LCS) protocol (RRLP) applies to GSM cellular networks. The RRLP protocol is used to exchange messages between a mobile phone and an SMLC in order to provide geo-location information, for example, in the case of emergency calls. The protocol was developed to fulfill the Wireless Enhanced 911 requirements in the United States. However, since the protocol does not require any authentication and can be used outside a voice call or SMS transfer, its use is not restricted to emergency calls. For example, it can be used by law enforcement to pinpoint the exact geo-location of any mobile phone.
RRLP supports positioning methods for mobile phones enabled with GPS as well as for mobile phones without GPS. For non-GPS mobile phones, RRLP performs an Enhanced Observed Time Difference (E-OTD) function, which is based on measurements inside the mobile phone, where the phone measures the observed time difference of arrival of bursts of signaling (SS-7) sent by nearby pairs of base transceiver stations.
Cellular network towers have GPS receivers (or a base station nearby) and those receivers are constantly pulling down satellite information and computing the data. This data is then passed on to the cellular phone whether the phone is GPS enabled or not (when requested by the phone via SS-7 signaling). The RRLP information gathering method is ideal for tracking the location of a multitude of applications where the pinpointing does not have to be exact, and where the device is not GPS enabled.